How to get Rect or Size by QStyle?

[nifei]

Hi, all.
I subclass QTableView and reimplement

QTableView::mouseReleaseEvent(QEvent *event)

QTableView::mouseReleaseEvent(QEvent *event)

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, in which i get

QTableView::currentIndex()

QTableView::currentIndex()

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and the event pos by

event->pos()

event->pos()

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before this i've set some items checkable so there is a checkbox in the responding positions.
Now, i'm wondering how can i get the checkbox's geometry, rect or size? which is devided from the item's other part. as in the attachment, i want to know the red rectangle's rect or just size.

By now i can get the whole item's rect through it's index and the style of this view. by the way, the view's indicator's appearence is set by a stylesheet.

thank you.